1. Field of the Invention
The present invention generally relates to a fluid shut-off valve for filling above ground storage tanks, and a sight and multiple switch indication for the level of the fluid that is being filled.
2. Description of the Prior Art
The days of the in-ground storage tanks are numbered. The world at large and environmental groups in particular are pushing for less pollution of the ground water emanating from leaking in-ground tanks that are not easily monitored to detect these leaks. Above ground tanks are becoming more practical. Especially with the tank in a tank design whereby the outer tank is monitored for moisture from the inner tank, and the installation of above ground tanks with moats around them that can be monitored for moisture.
The majority of shut-off valves to date generally relate to ones being used with in-ground tanks in which the fluid being fed into the tanks is gravity fed with large diameter hoses resulting in a filling pressure that is less than with above ground tanks that are pump charged through smaller diameter hoses. Above ground tanks are not necessarily in close proximity to the filling truck, therefore the smaller diameter longer hose with higher pressure is used to attain a satisfactory filling time. The smaller hoses are charged with filling pressures in the order of 70 to 120 psi and flow rates in the order of 200 to 300 gallons per minute. When using an in-ground valve to shut off a fluid in an above ground tank the valve will often snap shut when the tank reaches the desired filling capacity. This causes the charging pump to have an excessive amount of pressure that can damage the pump or other items used in the filling process.
New valves are now on the market trying to solve these problems. It is ironic though that for a shut off valve to operate properly it must shut off the fluid under high pressure and then leak under low pressure or flow in order to drain the filling hose. This calls for a unique type of valve designed just for this purpose.
One such device is disclosed in U.S. Pat. No. 5,207,241 Babb, this patent discloses that the float is used to over come the hydraulic moment when the valve is closing to keep the valve from snapping shut. This is referred to in the patent when discussing the operation of the valve, stating, "greatly reduces the hydraulic moment". To over come the hydraulic moment in the valve a large cantilevered float is used to close the valve. This then makes the orientation critical if the filling tube in the tank is near the end of the tank. If care by the person installing the valve is not taken, and the valve is oriented with the float toward the close end of the tank, the float will be restricted in movement thus not shutting off the fluid. After filling the tank and the pump is shut-off there is fluid in the filling hose. There are two ways to approach this problem, one, by using a dry disconnect, one that traps the fluid in the hose, or two, by letting the hose drain into the tank. The dry disconnect is an added costly part. In the Babb valve there is a gravity operated valve in the valve body that is to be used for draining the hose. This valve closes with the least amount of flow through the valve, thus making it impractical to be used for draining the filling hose. Another disclosure in the patent is the use of large bearings to overcome the filling and shut-off pressure of the fluid.
Disclosed in U.S. Pat. No. 4,605,201 Miyazaki, is a butterfly valve that closes on a taper to wedge the valve closed and to create an improved seal.
Disclosed on the market and marked patent pending is a valve manufactured by Guillotine. This valve has a coaxial mounted float in respect to the filling tube that addresses the orientation of the installation problem. The design of the valve is such that when the valve starts to shut the float works against the incoming pressure of the fluid until the float over comes the incoming pressure and then snaps shut. The design of the valve also allows clearance in the shut-off area of the valve allowing it to have excessive flow under high pressures when in the off position.
To date there are no valves that shut off the fluid and give an indication of the level of filling. There are federal guidelines in the works to mandate that above ground tanks have a visual and audible type of level indication for each tank when the tank fluid gets to approximately eighty-five percent. These tanks, because of being above ground, are not intended to be filled because of the possible temperature differential between the fluid and the tank. The state of the art to date includes two methods. One being, a clear tube that is attached to the end of the tank at the top and bottom to show the level of fluid. It may not be obvious in a tank in a tank design, of the complexity of getting the tube through the outer tank to the inner tank without having a leak, near term and long term. This also leaves the tube exposed to anything at ground level to damage it, i.e., fork lifts, work persons, etc. The second are sophisticated electronic devices that monitor the level of the fluid from an opening in the tank. These are costly because most have been designed for leak detection in in-ground tanks and must be very accurate. Because they were designed for minute changes due to small leaks and not the large level changes that take place during a filling process.